Essential Appositive

He told AFP the Forest Service usually does not drop the retardant in waterways and areas home to endangered animals -- unless the fire is threatening human life or public safety.

同氏はAFPに対し、森林局は通常、火災が人命や公共の安全を脅かす場合を除いて、水路や絶滅危惧動物の生息地に消火剤を投下しないと語った。

The word "home" functions as part of a noun phrase acting as an appositive or a supplementary noun that renames or further describes "areas."

The part "home to endangered animals" explains what kind of areas the Forest Service usually avoids dropping retardant in. It essentially means "areas where endangered animals live."
You can often replace such phrases with a more formal adjective phrase: "areas inhabited by endangered animals" or "areas that are habitats for endangered animals."